1. Field of the Invention
The present invention relates to a disk brake of a slide calipers type used as a wheel brake of an automobile and, in detail, to a mounting member for a disk brake in which a low frequency brake squeal is hard to occur.
2. Description of the Prior Art
There are known various structures for a disk brake of a slide calipers type which is used as a wheel brake for an automobile. In recent years in which reduction in weight of automotive parts has been promoted in order to improve the fuel efficiency and power performance of the automobile, a leading disk brake of a slide calipers type has such a structure as set forth in, for example, the TOYOTA ARISTO Repair Manual (published by Toyota Motor Mfg. Co., Service Div. on Dec. 1, 1991), on pages 8-37 to 8-56.
A mounting member for the above disk brake of a slide calipers type is a single member which, as shown in FIGS. 25 to 29, comprises: a pair of inner arms 1A and 1B respectively including torque receiving portions 1Aa and 1Ba for receiving a brake torque given to an inner pad (not shown) to be pressed against the inside surface of a rotor (not shown) rotatable integrally with a wheel (not shown), and also including, in their respective inner end portions in the rotor radial direction, mounting portions lab and 1Bb for fastening and fixing the inner arms 1A and 1B to the non-rotary parts (not shown) of an automobile such as a knuckle and the like by use of bolts (not shown); a pair of outer arms 1C and 1D respectively including torque receive portions 1Ca and 1Da for receiving a brake torque given to an outer pad (not shown) to be pressed against the outside surface of the rotor; a pair or connecting portions 1E and 1F respectively extending in the rotor axial direction in the outer peripheral space of the rotor and connecting the respective rotor radial direction outer ends of the two inner arms 1A and 1B integrally with the respective rotor radial direction outer ends of the two outer arms 1C and 1C; an inner bridge 1G extending in the rotor chord direction and connecting the respective rotor radial direction inner ends of the two inner arms 1A and 1B integrally with each other; and, an outer bridge 1H extending in the rotor chord direction and connecting the rotor radial direction inner ends of the two outer arms 1C and 1C integrally with each other.
In the above mounting member, when applying the brake in the car, the brake torque to the inner or outer pad is applied to the inner arm 1A and outer arm 1C or to the inner arm 1B or outer arm 1D according to whether the car runs forwardly or backwardly and, due to presence of the outer bridge 1H, the brake torques applied to the inner arm 1A and outer arm 1C (or the inner arm 1B and outer arm 1D) are distributed to the inner arm 1B and outer arm 1D (or the inner arm 1A and outer arm 1C). When compared with a mounting member of a type that the brake torques applied to the inner and outer pads are received only by the inner arm 1A and outer arm 1C or only by the inner arm 1B and outer arm 1D, the amounts of displacement of the inner arm 1A, 1B and outer arms 1C, 1D due to the elastic deformation of the mounting member 1 are small.
In the conventional mounting member 1 shown in FIGS. 25 to 29, the shapes of the inner arms 1A and 1B are determined mainly in consideration of the fact that the inner arms can deal with a bending moment caused by the brake torque applied to the inner pad. Thus, as shown FIG. 27, the dimensions of the inner arms 1A and 1B in the rotor shaft direction are smaller than those of the mounting portions 1Aa and 1Ba in the rotor shaft direction. And, the respective portions of the inner arm 1A, which receives the brake torque when the car is running forwardly, correspond to the bending moment caused by the brake torque applied to the inner pad and, as the inner arm 1A portions approach the mounting portion 1Aa, they have greater sectional secondary moments I. Also, the section shape of the outer bridge 1H is determined mainly in consideration of simply connecting the outer arms 1C and 1D to each other and, basically, the outer bridge 1H has a uniform section shape.
As for the disk brake as the automotive wheel brake, efforts have been concentrated on the control of the brake squeal in order to reduce the noise of the brake as well as the displeasure of a driver and others due to the noise. As a result of this, the high frequency brake squeal that has been often occurring for long time can be controlled now by interposing a rubber-coated shim between the inner pad and a piston for pressing the inner pad against the rotor as well as between the outer pad and a calipers claw portion for pressing the pad against the rotor, or by interposing a shim with a grease storage portion between them, or by chamfering the respective ends of the friction linings of the pads in the rotor peripheral direction (see the above-mentioned TOYOTA ARISTO Repair Manual, Japanese Utility Model Unexamined Publication No. Sho 60-58936, and Japanese Utility Model Unexamined Publication No. Sho 60-58938).
However, in the above-mentioned disk brake including the mounting member shown in FIG. 26 to 29 and other parts, the size or weight reduction thereof, the use of other material than asbestos in the friction lining, the weight reduction of the wheel peripheral parts of the automotive chassis, and the like have produced an ill effect as well, that is, the increased occurrence of a low frequency brake squeal (when compared with the high frequency brake squeal, the sound pressure level of the low frequency brake squeal is by far the higher and reaches far away). And, no effective measures have been so far developed against the low frequency brake squeal, which does not impede the promotion of the weight reduction of the brake disk and the non-use of the asbestos in the friction lining.